1. Field of the Invention
The present invention relates to a lateral drilling system, a lateral drilling tool and a method for drilling laterally from a vertical bore hole in the ground to bore lateral holes, termed herein as “roots” or “lateral roots.”
2. Description of the Related Art
There have been many attempts to design a device and method for laterally drilling from a vertical bore hole. U.S. Pat. No. 3,301,337 to Vaughn et al, issued Jan. 31, 1967, describes an apparatus for completing a well by pushing a plurality of conduit sections laterally with respect to a bore hole in a formation. This apparatus uses a hydraulic piston activated with a sucker rod with a ten-foot long stroke that operates a twelve-degree wedge to insert successive one and a half inch long conduit pieces that can be perforated to allow fluid flow. The long-piston stroke design was introduced to generate high force to allow the tool to penetrate resistant steel casings and well wall material in oil and gas production operations.
In the Vaughn tool, power to an upper piston is activated by a vertical rod connected to the surface and activated by equipment at the surface. In this design, a significant vertical downward force is necessary to activate the upper piston. Such force requires a strong anchorage of the tool. The Vaughn design includes a set of serrated grips at the base of the tool that are wedged against the casing prior to operation of the tool. Such gripping of the inner hard surface of the area to be drilled can be expected to be effective on hard surfaces, i.e., rock or the inside of a well casing. In softer soil such as clay or silt, where steady gripping is not possible, this requirement for gripping of rock for bracing would make this Vaughn design unusable or at least very impractical.
Similarly, when upwardly thrusting the wedge during the pipe insertion phase, the tool would tend to be pushed downward. This downward push would be expected to occur even if hydraulic power were supplied from the surface through a hydraulic power line. The Vaughn design includes the lower grip portion of the tool to immobilize the tool. Under the intent of penetrating softer soil, anchoring the tool to the side of the bore hole cannot be achieved effectively, and the wedge's upward thrusting energy would be commensurately lost to downward slide of the tool, reducing the intended force of penetration. Besides the loss of penetrating power, this downward push under the Vaughn design in soft soil would also result in vertical displacement of the tool due to unsecure anchoring. This vertical displacement would cause an inability to align each successive pipe segment to the previously installed pipe segment.
The Vaughn tool is operated by a sucker rod to activate the piston. That sucker rod must be activated from the surface with a drilling rig or heavy pipe handling equipment. The tool requires a cap at the upper part of the tool as part of the control of the sucker rod used to activate the piston. The cap appears to prevent the option of a removable pipe segment rack.
A wedge-activated system such as described by Vaughn results in pipe sections only about one and a half inches long, because of the spacing requirement of the Vaughn wedge and anvil components. The spacing requirements for the wedge and anvil also would appear to preclude a side-by-side installation of two pipe inserting units.
U.S. Pat. No. 5,622,231 to Thompson, issued Apr. 22, 1997, is directed to a method for forming substantially lateral bore holes from within a vertical shaft, with a rotating drilling tool. A drill bit is gradually pushed farther into the lateral bore hole by successive insertions of shims. This system uses a rotating bit to drill the lateral bore and is complex.
U.S. Patent Application Publication Nos. 2005/0167160 and 2007/0151765 to Billingsley, 2005 and 2007, respectively, describe a drilling tool operated as a hydraulically powered drill bit to insert successive three-inch segments. This system also uses a drilling bit and is a complex device.
U.S. Patent Application Publication No. 2008/0164065 to Orban et al, 2008, discloses an on-site fabrication of a tubular member formed from a rolled band of metal that is used as a drilling bit.
U.S. Pat. No. 6,561,732 to Bloomfield et al, issued May 2003, describes construction of lateral pipes, including the use of slits and other configurations to allow passage of fluids.
Other patents such as Bond (U.S. Pat. No. 6,276,453), Jelsma (U.S. Pat. No. 7,422,059), Kimura (U.S. Pat. No. 4,936,709) and Schmidt (U.S. Pat. No. 4,671,703) relate to certain aspects of bore holes and/or lateral drilling.